” Cartilage doesn’t heal” This is what doctors tell us when we injure our flexible tissue, which lines our hips and knees, or when osteoarthritis has caused it to erode so that our joints feel painful when we move. Orthopedic surgeons have explained to me that cartilage does not have blood supply to replenish nutrients and repair cells at injury sites. It’s still a strange thought that living tissue can’t replace damaged cells. Recent research has shown that articular cartilage, the type found in our joints, may have limited repair capabilities. This ability is a source of hope for treatments that can improve healing and protect damaged cartilage from further damage.
To visualize articular cartilage, imagine the hard, white coating at the end of a chicken bones. It is mostly a spongy substance called extracellular matrix. This is a mixture water and fibrous protein that has been pumped out of cells called chondrocytes. Virginia Kraus, a rheumatologist at Duke University School of Medicine, explains that there is intrinsic regeneration. New tissue is formed and old tissue is removed. This is the same as for all tissues except tooth enamel. She emphasizes that cartilage’s renewal process is slow. It is true that adult cartilage has no blood supply. Dynamic loading, which experts refer to as putting stress on the joint or weight on it, causes synovial fluid to flow in and around the joint. Kraus explains that exercise is crucial for joint health. “Movement .”
is the best way to get nutrients to cartilage.
Kraus, one of a few scientists who study the slow turnover of this tissue, is one of them. In a surprising discovery, she and her team reported in 2019 that the production of proteins associated with repair and regeneration differs by joint: It is greater in the ankle than in the knee and greater in the knee than the hip. Kraus calls this “our inner salamander”, explaining that animals such as salamanders can regenerate a limb and that this ability is stronger in the foot than in the leg.
Her research also revealed that the genetic material involved in repair is more prevalent in arthritic than healthy joints. Kraus believes that osteoarthritis is launching a repair program in humans just like a limb injury in a salamander. However, “obviously the programme we have isn’t sufficient.”
There is additional evidence that human cartilage can be regenerated. Joint distraction is being used to promote healing in patients with bone-on-bone arthritis. (Prosthetic knees last 15 to 20 years, after which they must be replaced in a complex surgery.) This procedure involves placing pins above and under the knee and using an outside device for six weeks to remove the lower and upper leg bones by five millimeters. This opens up the joint space. Patients are encouraged to walk but the device reduces stress so the knee is soaked in nutrient-laden fluid.
Dutch researchers have shown that the procedure leads to a small increase in cartilage in the joint and less pain–benefits that last at least two years and as many as 10 in some patients. Philip Conaghan, a rheumatologist at the University of Leeds in England, said that larger clinical trials are needed to validate the technique.
Conaghan studies new drugs for arthritis. He is particularly interested in a growth factor called Spifermin, which appears slow down the loss of cartilage among some patients .. He is also looking at canakinumab, an inflammation inhibitor that was tested as a cardiovascular drug and showed a surprising side effect: dramatically fewer joint replacements in recipients than in a placebo group. Conaghan warns, however, that it is difficult to find drugs that can thicken cartilage because of the slow, uncertain nature of repair.
For those with fraying joints, strength-building exercises are still the best strategy. Conaghan suggests swimming in a pool. He says that strong quads can reduce knee pain no matter what your life is like. “All of life is about strong muscles.”